Showtec Light Bar 12 Parts

[dmxlights]

Hi Rob,

I have been looking at some scrap boards I have even they are not of lights to find a donor none yet.

 

I do know that mosfet only controls the blue of that one led as it is a pixel bar. I am very tempted to put BC547. Also the main power supply is 5v only (had to check this)

 

 

Seems like it could be a MOSFET, although I can't quite work out why your beeping appears to show a ground at both ends.

 

 

 

 

oops. That was meant to be 5v not Ground going to the led

So you've drawn your LED back to front too. Anode to +5 and cathode to the drain of the MOSFET. If it really is run from only 5V and there is a 30 ohm resistor in series then you can't possibly have more than 170mA flowing through it, even with zero Vf. You need a relatively low Vgsth so something like a BSH108,215 or a DMN6140L-13 are only 15p each from CPC (provided you've got something else to order at the same time) and are complete overkill! I've only picked those as they were at the top of a parametric search and in stock - there are dozens of others to choose from.

 

Thats a big oops. I did blind myself when pining things out I managed to blind myself when I went to check current draw of the led which could explain my mistakes.

Thank you also for the part number I will look them up

 

[indyld]

A trick I use for testing these kinds of LEDs in place, and also checking polarity when replacing them, is to power a colour at the LED terminals using diode test mode on the meter. It usually provides enough juice to get the junction to glow and the probe orientation confirms the polarity. Edited October 26, 2021 by indyld

[Don Allen]

The diode test voltage varies with budget multimeters, so they may not light all led's, which can give a misleading result. The blue led's have a higher voltage drop, around 3v than red led's around 2v. I use a second multimeter to measure the diode test voltage of a multimeter.

 

I was searching for an smd part number for a Martin Rush MHD led driver that had a small tab in between two legs on one side and three legs on the other side, marked 6655 C398, went looking for a FET and discovered that it was a LED Driver which adds another possibility when looking for parts. Mouser search

[dmxlights]

I would like to thank every one who has post help. I know the led can be tested the the diode test on multi meters and I know the multi meter I use will work on most leds.

 

 

Also I have check the other leds and it is a mosfet/transistor.

 

I have also order some BSH108,215 that DrV has posted above. I will post the results when I have got them and fitted to let you know the results.

 

[dmxlights]

I would like to thank everyone who posted and help for the mosfet BSH108,215 came today.

 

I have replaced the faulty one and all is working fine now. Nice to have that bar back working to it full and I have some spares for them if I have any problems again.

 

Thank you all again who posted